The goop and the mudcano

Akhtarma Pashali Mud Volcano erupts in Azerbaijan. It may be the most impressive mud volcano eruption in history. Boyuk Khanizadagh also produced flames of this size when it last erupted, so it is not a one off.

On Wednesday I was asked to look into the possibility that there had been an eruption on the West Coast of Sweden. It was one of those phone calls that are really confusing and making you wonder if it is you, or the rest of the Universe, that has gone utterly bonkers.

Since it was an official request I had to go and take a look at things. But, let us begin from the beginning.

The goop

On Monday 16/4 2018 a lot of coastal residents in the islands around Gothenburg started to call the Swedish Coast Guard about a suspected oil spill. A distance of 150 kilometres was inundated by grey globs and water with light grey suspended goop.

The Coast Guard quickly came to the conclusion that it was not an oil spill, and sent samples for laboratory testing since they suspected that it was some sort of algae bloom of unknown origin. Simple microscope studies gave at hand that there was no algae to be found in the samples. In fact, there was no organic structures at all in it.

Goopy mud on the coast. Photograph from Aftonbladet.

And this is consistent with deeper sediment layers. Yes, they started out as organic sediments (mostly), but over time all organic structures will be removed and only the organic base products will remain.

It was about that moment I was called in to take a look at it, and I must admit that I was rather amused as I went. The idea of a volcanic eruption in the waters outside of the Swedish West Coast is pretty hilarious, if you know your geology.

As I came to the coast and started to look at the goopy lumps and the greyish water I had a feeling that I had seen this before in other parts of the world. The lumps were like modelling clay, and the suspended grey material had a distinctly muddy look to it. The surprising part was that the lumps floated in water.

In the call they had said that it was like ash covered in fat. But, as I looked closer it was just very finely ground clay, and that can feel quite fatty as you handle it. And as I stood there I understood what it probably is, and that I had indeed seen it around the world.

The mudcano

The most famous of all mudcanoes, Lusi. Photograph by Hugh e82.

The most famous example of a mudcano is of course the Sidoarjo mud flow that created the Lusi mudcano. Another famous example is the Fiumicino Mudcano near an airport outside of Rome.

The point central of mud volcanism is Azerbaijan, it holds about 40 percent of all the 1000 known mud volcanoes around the world. Normally mud volcanoes are small and never reach the size of their magmatic namesakes. That being said, a couple of the Azerbaijani versions are ten kilometres across and 700 metres tall.

They are caused as methane is heated, or ignited, and as the methane expands there will be an explosion that hurls clay and mud into the air or pushes it out in a slower fashion as a mudflow. Sometimes these eruptions are accompanied by large flames of burning methane.

The good part of this is that you most likely have a deposit with hydrocarbons in the vicinity, either as natural gas, or as coal or oil.

Even though the hyperbolic press found it all to be unknown, unheard of, and a new thing, it turned out that this has happened before along the same stretch of the coast. Last time it happened was on the 27th of November 2017, but earlier finds are also known.

This also strengthened my belief that we are dealing with a mudcano out in the waters. There are also known deposits of hydrocarbons out there, but they have been deemed to be commercially unviable.

I also checked seismological data for any signals that might point towards this being volcanic in origin just to rule out any black swans. And as I suspected there was nothing to be found in that regard.

A couple of weeks ago I wrote about magma residing under Norway, so I thought I should put the probable mudcano into perspective to that. Most likely these two phenomena are unrelated since there is just too much bedrock for the magma to go through to come near a deposit of methane.

Any methane deposit would reside at a fairly shallow depth with a maximum of 4 kilometres. And the magma under Norway is residing at a depth of more than 44 kilometres. It is though possible, even if it is farfetched, that there has been a dyke formation quite some time ago, and that this has warmed the deposit of methane.

Conclusion

The Fiumicino Mudcano outside of Rome.

Is this dangerous? Yes and no, mudcanoes are in general rather benign and slow features impacting local life only. But, in this case it is in the ocean, so if the methane outlet is big enough it can lower the buoyancy of the water directly above it, and that can be a hazard for smaller ships.

The second thing is fairly obvious, it is not good with a lot of goopy mud in the gills of fish. This may take out a season of fish spawning. Otherwise we should be good.

hmm that comment altered by wordpress – so the first link was meant to have the text below (I’ve added the blocks with spaces into the link to break it up – so that hopefully it doesn’t get trimmed now)

hmm just looked at the previous article – the images there show fine – albert looks to have uploaded slightly differently – he looks to have used i2 rather than i1 and jpeg rather than jpg and no underscore in the filename – and fixed width rather than dynamic width (I wonder if that’s it? surely chrome+mozilla can handle that)

The problem with oceans are that they are big, and currently the Coast Guard is not overly bothered to look for it.
But, judging from prevalent winds and currents the location is somewhere 60 kilometres outside of Gothenburg within a radius of 30 kilometres or so.
Basically we have to wait until a captain of a vessel report in something interesting.

60 km out from Gothenburg is almost on the Danish coast! The prevalent wind last week was towards north and similarly the water current along the Swedish west coast is towards north. Taken that together we lands somewere around the island Laeso in Kattegat..

Actually, given that there was recently an article about volcanoes in Norway in the not too distant future, what is the likely time period that eruptions could start happening? Is this something imminent (less than 1 million years) or something that is going to take place in the more distant future. Same for the New England magma body, is that getting close or is it still a way to go?
I’m actually surprised there weren’t more of these sorts of questions on the original article, it is probably one of the better recent posts in terms of originality.

A mantle plume below Norway causing uplift of the Caledonian structure there, just like a mantle plume below the Variscan structure caused the uplift of the Rhenish Shield and volcanism of the VulkanEifel region. But why hasn’t magma below Norway broken to the surface yet, in contrast to the magma below the Eifel region which has already broken to the surface several times?

The Norwegian volcanoes are likely to come into play within the next million years due the larger geological effects.
The New England magma is more looking like a dud since the continental US is happily moving together with Icelands push, so no additional tectonic force is added.

We have ruled out pretty much every other possibility by now in regards of it being a mudcano. And on top of that the setting is just a bit too good for it not to be a mudcano. All other remaining ideas is just too far fetched.

My neighbors fishermen that has lived here on the islands for generations told me they have seen this floating stuff many times before. If it is a submerged muddcano, this suggest frequent eruptions. Problems now to track down mutations. Wind directions has varied a lot the last weeks. Streams remain relatively constant.

I guess we still have Iceland but given how Norway and Sweden are thick granite crust the eruptions will probably end up mostly being pretty silicic and more likely to form calderas, compared to basalt lava flows in Iceland, so there probably would be actual VEI 8 supervolcanoes there one day.
Maybe the first one will be like a kimberlite eruption, a brief explosion that makes a small crater or cone only on the scale of a large house. I guess over time bigger eruptions will start happening and maybe the first big eruptions will be flood basalts, which over time transition to rhyolitic volcanism and calderas.
Maybe one or two of those have already happened and it just occurred during the last ice age so there is little to no trace of it now, and the small amount of erupted lava was dispersed so much by the ice sheet that it is practically impossible to distinguish from ground granite bedrock dust.

Maybe in 10 years there might suddenly open a big rift down to the mantle and a flood basalt starts and erupts 1000 km3 of magma over the next few decades, eventually forming a new lava field that is the biggest lava flow in the last 15 million years, bigger than all the magma erupted in Iceland in the last 10000 years, and fills in the Oslofjord and flows across Sweden to bury Stockholm as well, and all the magma-water interaction causes such an ash cloud that it covers all of northern Europe thick enough to ruin the agricultural season… Top that yelowstoners 🙂
That black swan would make black holes look shiny, but quasars are shiny black holes so 😉

Actually I did some maths, and to erupt 1000 km3 of magma in 30 years the eruption rate would have to be 0.09 km3 a day, or 90 million m3 per day. Which means this hypothetical eruption would erupt the volume of mauna loas 1950 eruption in about 4 days if it went at a constant rate the whole time. If it behaved like a normal eruption with the start being more intense, it would obviously blow this number way out of earths gravity well. That being said, the eruption rate at 90 million m3 a day is 33.3 km a year, which is ‘only’ about twice the volume of the skaftar fires eruptions in 50% longer time, so not totally beyond what we already know.

I also hope someone from a fake news website doesn’t read my comment and do an article about how Oslo and Stockholm are going to be buried by lava in a decade. I dont even think a 40 km deep rifting fissure through a craton is actually possible without the craton breaking up completely first.

Overlook crater is overflowing again, more substantially than last night and comparable to the 2015 flows.

Really the only way I can see the situation at kilauea ending is with a major break in the system. This has gone beyond the situation in 2016, 2014, probably even all of the 2011 breakouts, and the overlook crater didn’t exist in 2007 or 1997, so we are in uncharted territory now.

Thank you Carl for this excellent article. Methane and clay is an interesting addition, to the theories needed to explain mud volcanism, and the depth and time scale is intriguing. The petrified forests we have on our shores here are under sand and over clay. I have argued that the clay floats, and so protects us from some of the effects of rising sea levels, but there was no scientific reasoning that I could call on to support my hypothesis. Some time ago I was arguing that building on the clay over our local salt marsh ought to be on a mulberry raft. They put steel pillars down 74 feet instead to solid rock…. You may also recall that I linked to an unexplained fire on the marsh that covered a couple of square miles, started at 4.00am, in pouring rain after days of rain and stopped when it reached the area of thicker clay. I am even more intrigued now if this is leading to a possible hypothesis and would be interested to know more

Lovely…. just lovely….. looking at the first picture my first thought was… well that doesn’t look like any eruption i’ve seen and it isn’t…. didn’t know mud volcanoes could be so impressive. ((got the rubbed pork in the slow cooker and waiting for grandchild to get ready for school…. i’m the driver… and i’m promising the next grandchild to live with me and finish high school must walk or drive themselves!!… i’m getting way too old for this!!))… Best!motsfo

But presumably not under salt water? Fresh water cuts through salt clay? And salt re constitutes quick clay….? We have had news recently that a new creek is cutting a channel of quicksand through a section of the wide sandy estuary mouth from the river nearby. This is very informative. Thank you!

The messed up bit is that the description of the floating balls of goop match the oil turds I saw in the Persian Gulf in 1983 when an oil platform got popped by Iraq.

At the time, Iraq couldn’t send a crew to repair it because Iran would shoot at them, Iran couldn’t fix it because Iraq would shoot at them, and Kuwait couldn’t do it because they would both shoot at them. Dunno what ever became of that.

This looked very much like old oil spill but analysis showed it was not. No obvious smell, will not catch fire even if heated with open flame, floates on water, feels a little greasy but was obviously not oil related.

Just watched this video that was posted on the weekly volcano watch report. What is obvious is the changes in the lava pond. After watching it again I noticed some movement in the foreground. Just left of center in the images you will see a larger piece of hardened lava continue to crack and the closer part settles down. Just to the right of the center you will see hardened lava moving up (and down) a little further away from the camera. Not sure of the focal length of the camera so not sure how close this is to the tripod.

A historical record of east-west tilt at Kilauea in the years before the current eruption. This is from Fiske, 1969, in Science

‘S’ indicates summit eruption and’F’ is flank eruption

About the actual summit eruption, they write

“The tilt was steady during the last several hours of 4 November and the first 1.5 hours of 5 November 1967. At about 01:33 on 5 November, strong harmonic tremor began recording on the seismographs near the summit, although no change in the tilt was detected. Shortly thereafter, at about 01:45, the tilt increased
at a rate of about 0.75 microradian per hour-a rate greater than any recorded during the entire 221/2-month inflation. A felt earthquake rattled through the summit area at 02:04, followed by another at 02:20. These two earthquakes originated about 4 to 5 kilometers below the summit of the volcano. If our estimates of depths to Kilauea’s magma reservoir are reasonable ones, these earthquakes originated a full 1 to 2 kilometers below the magma reservoir. They, together with the accompanying harmonic tremor, were possibly caused by the sudden rise of new magma from depth into the shallow, highly swollen reservoir complex. Meanwhile, the tilt continued upward at its high rate. Within minutes, the reservoir could accept no more; magma forced its way
upward, split north-south fissures across the floor of Halemaumau, and spilled onto the surface at 02:32 on 5 November, to begin the 1967-68 eruption.”

The situation is rather different now, but it shows how quickly things can develop. Hekla-like.

In any other volcano a magma drain like what happened in 1960 would have shut it down for decades, but yet kilauea erupted multiple times within a year of that event, and within a decade it had an even bigger eruption… I guess when the magma source is the second (third?) most powerful mantle plume on earth then things could happen faster than expected.
That being said, the galapagos volcanoes might outpace it though. In 1979 sierra negra volcano erupted at least 1 km3 of lava in only 2 months, and most of it was within the first few weeks. That is the sort of eruption rate that you would expect from an Icelandic flood basalt eruption, not a pacific island shield volcano.

Also by technicality the overlook crater is a vent in this current eruption, so if it continues erupting after pu’u o’o shuts down, would the current eruption be considered to be ongoing or would it end with activity at pu’u o’o and the summit activity be considered a different eruption?

This is all true, but the point still remains, a ‘typical’ hotspot island shield volcano managed to pull off an eruption that compares to a major Icelandic rifting event.
Most lava eruptions on island volcanoes are compared to mauna loas 1950 eruption, but that was literally dwarfed by the eruption in the Galapagos. It was very probably the biggest lava eruption in the southern hemisphere in recorded history. The eruption rate required to erupt 1 km3 of lava in 2 weeks is over 3500 m3/s of lava, in real life it would have been less than this but not much less (probably still well over 1000 m3/s), and all this erupted from a vent that was basically at the summit of the volcano, not a gravity driven flank vent.

Nice article! As a fellow Swede, I would never have guessed we have a mud volcano in the neighbourhood. It would be nice to have it confirmed, or even better to have its location pinpointed.

By the way, don’t you think it’s time for another large quake from Bárðarbunga? If you go by the average energy release from the last few big ones, there should be enough strain built up by now since the last one for something approaching an M5…

Petrochemical data is congruent with mudcano products.
But as far as pinpointing it we are out of luck.
The Coast Guard has declined to look for it, the same with Navy.
At best the Merchant Marine Authority (Sjöfartsverket) will look for it during their 2019 campaign.
I have been ranting on the phone for more than a week now to get them to actually work instead of polishing the knobs of their shiny boats. No luck so far.

Here is a satellite image of April 19. Is this your gloop? If so, you can see where it comes from: on the coast of Norway, south of Lyngdal. But it could just be cloud, of course, although in that case the point of origin is remarkably clear.

If what we see in the picture is our goop, it probably does not originate from Norway since the sea currents go the other way. I stole this image off a webpage about plastic junk drifting in the sea. The general directions are probably not limited to plastic junk but should also apply to mud volcano goop.

Taking in the wind and sea current of Kattegat during the week before the stuff landed on the shores, I get it down to somewhere between the Danish islands, Anholt and Laso. However, I do not know how long strech of the coastline that received the stuff…

Using data from this lecture, apparently full margin failures of the Cascadia are from 499 to 581 years recurrence {99.5% conf interval}, but southern segment {Oregon → Nor California} failures are about every 243 years. (Not enough data for me to calculate a confidence interval)

Sidenote; a Mag 9.0 yields around 631 km of subsurface rupture length, 9.1 → 721 km. (From the source text of the formulas, “Reverse Slip data is not significant at the 95% confidence interval”) In other words, take it with a grain of salt because it might be incorrect. But, in a nutshell, what I have seems to point towards “full margin failures” being about Mag 9.1 when they happen.

This gif shows the uplift of pu’u o’o over just the last 4 days, I would give it a week at most before something gives. The other side of the crater is almost 300 meters away from the camera, so the uplift in the last few days is probably at least 10 meters in the last 4 days, added to the past few weeks of additional uplift and the rising lava pond in the west pit.
My guess is that if the breakout is on pu’u o’o then it would be significantly bigger than the 2014 and 2016 breakouts, but with halemaumau overflowing now the potential for a breakout on the east rift is probably just as likely as a new flow from pu’u o’o. I dont see it being likely to end in an intrusion because all that magma would have to do is break out of the pu’u o’o conduit system that already exists, like what happened in march 2011. My guess is that the breakout will either happen uprift of pu’u o’o in the are of the 2011 fissures, or it will happen slightly to the northeast of pu’u o’o as an initial flood of lava like in august 2011, which would likely endanger lower puna. Either way it will be quite a show.

I found a picture from 2011 that I think best compares to the situation now:

It looks like the crater floor was much more deformed than what is happening now, and it was, but when this picture was taken none of the extensive northeast directed crater overflows (kahualea 1 and 2 flows) had happened yet, so both the spot where that picture was taken and the perched lava lake in the picture would actually be underground now by a significant degree (at least 20 meters). The crater floor now is by far the highest it has ever been in the eruption, and the doming of the inner crater floor has probably reached a level height with the outer edge of the crater (about 90 meters above the 1983 terrain). The above picture was taken only 4 days before the August 3 2011 breakout, so the current situation might have only a few days left before something gives, the longer it takes, the bigger it will be in the end.

By this point the only black swan would be if this activity DIDNT do anything…

Well there is already an open vent in the caldera so I dont think an eruption would happen there (which is probably why there was no eruption after the high lake levels in 2015), but an eruption along the southwest rift is plausible, as long as it is at or below the level of the lava lake.
An interesting place for an eruption that hasnt been discussed yet would be kilauea iki. the crater floor (1959 lava lake) is at a lower elevation than the floor of halemaumau and the outer caldera, and there is supposedly a shallow (<1km) connection between the two areas as shown by the 1954 and 1959 vents lining up, and part of the 1954 vents experiencing deformation during the 1959 eruption. Vents also opened along this like in the 1970s and in 1982, so there is probably still a pathway there. Kilauea iki is very accessible and is also a deep crater, so an eruption there would probably be pretty well observed.

This overflow looks more substantial than the previous ones. At the right side of the lake the lava is visibly flowing out enough for the lava to not crust over immediately. Given the size of the lake this lava must be flowing at least 50 meters while remaining incandescent, so not a small amount of lava, or a slow moving flow. I would actually say that a lot more lava is erupting from the lake at this time than is erupting at pu’u o’o, which could be a significant change in the long run, or lead to an even bigger breakout at pu’u o’o than the inflation there already suggests.
The lake is a >200 meter deep ~220 meter wide cylinder of lava, which would contain 7.6 million m3 of lava on a low estimate (200 meters deep, 220 meters wide) and 14.7 million m3 of lava at a high estimate (300 meters deep, 250 meters wide), HVO have confirmed that it is the biggest lava lake on earth right now. I would compare it to an overflowing dam with a hole in the side that is poorly sealed. It isn’t going to empty by overflowing out the top and theoretically the entire thing could drain into the east rift and erupt at pu’u o’o at any time…

My guess is that at least 50% of halemaumau has been covered at this point by this overflow alone, and by the looks of things some of the overflows are becoming slightly more channelized than before, which might allow spatter ramparts to grow around the lake edges and increase its height.

Probably not a bad guess. We are seeing the 1900’s lava lake reforming. It is worth wondering why this is. Either the magma input has increased, or there is a blockage downstream. If there is a blockage, where is it? From the fact that pu’u’o’o is inflating, we can guess it is downstream from there: the lava flow out of pu’u’o’o has become restricted. And indeed, lava hasn’t been getting anywhere near the ocean for some time. Kilauea is responding to this. There may have been some new magma as well (two bursts of deeper earthquakes below Kilauaea earlier this year) but the main cause is downstream.

The most likely break-down will be at Pu’u’o’o, where the pressure is largest.

I would say it is more the 61g vent that has become restricted, much like what happened to the 61e (June 27) vent before it, and the peace day fissure in 2013. The rate of magma supply to pu’u o’o looks like it is still about the same as before, but there is no real outlet anymore, so the inflation started and breakouts from vents in the crater started. I would say that the summit activity is caused by a significant increase in supply rate.
A month or two ago someone on here reported on a stack of earthquakes near pahala, and someone else replied that they got a contact from HVO saying that part of kilaueas deep feeding system is in that area, where magma from the hotspot rises through the lower lithosphere. That could have been the precursor sign of the current activity. This doesn’t mean it is a brief change though, maybe the next year or more will be characterized by much more vigorous lava flows than have been seen in Hawaii for a while.

Last year I had a suspicion that something would happen this year, the June 27 lava flow lasted just under 2 years, so I thought the 61g flow might have a similar lifespan and that a new vent would appear in mid 2018. Well almost exactly on time a new very strong inflation of pu’u o’o started. I didn’t expect halemaumau to overflow at the same time though, or for the crater floor of pu’u o’o to visibly dome up to above the level of the cameras…

(To someone that can edit comments, if this picture is different to the one above, can you replace the picture above with this one? If it is the same though, or just a text line, then delete this comment)

With uwev, npit gps turning west and north. outl moving to the west and south. And most others in the area increasing in their normal movement to the east and south I would guess that the inflation is just under or to a little east of the caldera. If you go to the USGS earthquake map you can add an overlay that shows the faults.

I think the main deformation center is in the south part of the caldera, between the overlook crater and second 1982 eruption vents. This is where magma from the 2015 high lake overflows went.

I think the current layout of the magma system at kilauea is in two parts. The first is a shallow system that extends from the ocean near pahala up through mauna iki, through halemaumau and ending at kilauea iki. The second part is the whole east rift up to just south of halemaumau, and the southwest rift down to the kamakaia hills. The two systems roughly overlap at halemaumau where the overlook crater is. The koae fault system is also part of the magma system because dykes sometimes intrude into it, although only very small eruptions have happened there.

Pahoa will be safe if a breakout happened on the side of pu’u o’o, the final year of the June 27 flow was basically filling in the area of the north side of the rift zone. None of the steepest lines of descent to the north of pu’u o’o go anywhere near the crest of the rift zone now. They do, however, go directly towards the more expansive subdivisions that were previously safe because of the topography.

I couldn’t find it the other day, but one of the last maps of the June 27 flow had a overlayed line of steepest descent, and the lines went basically right into lower puns north of Pahoa.

If there are cracks already forming before any eruption has happened, then that is actually unusual, all the other flows since August 2011 have started immediately (literally within seconds) after the vent opens. Maybe this is a sign of a bigger breakout happening in the near future, the August 2011 breakout was a literal flood of lava (probably with even higher flow rates than a lot of the 1980s lava fountains) and managed to get about 7 km from the vent within a day, if that happens now then all bets are off…

Well as you rightly pointed out, the existence of the summit vent is a bit of a game changer; maybe it will simply be a summit eruption, infilling the crater and re-establishing a longish-term lava lake in Halemaumau,as existed in the 19th and early 20th centuries.

True, but in the early 19th century the magma supply rate was very high like it is now, and most of that time was caldera filling, but in 1823 and 1840 there were very big distal eruptions. The 1840 eruption was apparently the biggest eruption on the lower east rift in the last 2000 years, and was comparable to a mauna loa eruption in terms of eruption rate.
So a big lava flow at pu’u o’o is still completely plausible, and the inflation at pu’u o’o would probably do something anyway regardless of whether the summit is directly involved.
HVO staff will be looking at this years events for a while.

Interesting to note that all the ‘bell-ringer’ EQs on the ERZ stay uprift of Pauahi, while Pu’u O’o swells up like a woman carrying quintuplets. Must be that there’s no rocks to break downrift–mostly plastic or molten magma.

”This morning, April 24th, the National Institute of Geophysics and Volcanology (INGV) recorded an intense explosive sequence on the Stromboli Volcano, which involved the mouths of the central and southern area located on the crater terrace. A first explosion, which occurred at 11.05 local emitted abundant ash mixed with incandescent material and large lava blocks that fell in the summit area and along the Sciara del Fuoco. The products issued exceeded a height of 250 m above the crater terrace, as evidenced by the video surveillance cameras of the INGV-OE Etneo Observatory. This explosion was followed by a second explosive event at 11.06, characterized by a modest fountain. At 11.10, the closing event of the sequence with the launch of pyroclastic material of lower intensity, compared to the first explosion. Overall, this explosive sequence produced an ash cloud that was quickly dispersed to the southeastern quadrants of the island. The launch of coarse pyroclastic material was radial and fell back over the crater terrace and along the Sciara del Fuoco. Violent explosive sequences, such as the one described and classified as major explosions, also occurred recently, on 18 and 7 March, and during 2017, on December 1, November 1, October 23 and July 26. These are more violent explosions than those of ordinary Strombolian activity, during which coarse and ashes material is emitted, which falls in the summit area. These events, occasional and unpredictable, abruptly interrupt the ordinary Strombolian activity. However, they are part of the volcanic phenomenology typical of the summit activity of Stromboli, characterized by explosions of variable energy. The Stromboli activity is continuously monitored by the INGV through its sections of Catania, Naples and Palermo.”

Out of all the active lava lakes on earth right now, I would consider only this one and the one in nyiragongo to be actual ‘lakes’. Erta ale might be borderline, but all the other ones are barely ponds in comparison to kilauea and nyiragongo. Both are over 200 meters across easily.

Technically this lava lake is the second biggest permanent body of liquid in Hawaii by surface area, and possibly the biggest by volume. There is a lake on Ni’ihau island that is much wider but really shallow, all the others are small or ephemeral.

I would call that a lava hot spring, generally a body of water that active wouldn’t be called a lake anyway. Same with mt erebus and villarica, both of them are more like ponds than lakes. I can’t think of any more volcanoes that have a lava lake at this moment.